Tension is brewing between Cisco (Carlos Valdes) and Wells (Tom Cavanagh) in the upcoming episode of "The Flash."

In the episode titled "Monster," the promo shows that the technology wizard is seriously having doubts about Wells' true intention of being on Earth-1. Wells previously claimed that he came to ask for Barry's (Grant Gustin) help in training his daughter Jesse (guest star Violett Beane). She has suddenly started exhibiting powers of a speedster and Wells was worried that she would get in trouble soon. Although Team Flash took Wells' words at face value, there have been instances when the members, especially Cisco, could not help but feel that something is wrong.

As per the teaser, Cisco's suspicions seem to hold true when Wells gives Barry the wrong advice on how to deal with the monster causing destruction in Central City. Cisco looks at the scientist oddly, correcting him. Later on, he tells Barry that Wells has been behaving shiftily. The Flash cautions him about giving unfounded accusations. Cisco thinks he is right though, and when given the chance, he goes to check Wells' bag. Wells catches him in the act and scornfully asks if there is no such thing as trust in Earth-1.

Meanwhile, the synopsis (as per CarterMatt) reveals that Caitlin (Danielle Panabaker) will be desperate enough to ask for her mother's advice. The world-renowned Dr. Tannhauser (guest star Susan Walters) will be fascinated to hear that her daughter is starting to exhibit meta-human powers. She will not be able to help herself from looking at the situation as a biomedical researcher, which upsets Caitlin. The younger woman thinks she should act more like a mother to her. Caitlin is so angry she will rehash old arguments, triggering an ugly showdown between them.

"The Flash" season 3 airs Tuesdays at 8 p.m. ET on The CW.